On Fri, 8 Aug 2008, Mikulas Patocka wrote: > On Fri, 8 Aug 2008, Jens Axboe wrote: > > > On Fri, Aug 08 2008, FUJITA Tomonori wrote: > > > On Fri, 8 Aug 2008 08:15:37 +0200 > > > Jens Axboe <jens.axboe@xxxxxxxxxx> wrote: > > > > > > > > BTW, we also wait for your verdict on: > > > > > > > > > > http://marc.info/?t=121611935500002&r=1&w=2 > > > > > > > > I've always hated the iommu virtual merging complexity. My plan is to > > > > rip it out. > > > > > > No complaint from me. I'm just happy to see the verdict at length. > > > > Mikulas, you had a patch for this. Can you strip out the arch bits and > > just send me the block bits? The arch bits should go in via the arch > > maintainers. > > > > The iommu code may still do virtual merging, it would be silly not to do > > that if possible. Now that later kernels expose the necessary parameters > > at that level as well, it's perfectly feasible. > > Here I'm sending the first one, it removes virtual merge accounting from > blk-merge.c (it acts as if all architectures undefined > BIO_VMERGE_BOUNDARY). I also created second patch that removes > bi_hw_segments field from struct bio and struct request. The next task > would be to remove nr_hw_segments from the request_queue, but it will > require changing the drivers. > > Mikulas (note: raid5 uses nr_hw_segments field for some other purpose, so this patch will break it. It should be fixed by raid5 maintainers) Remove hw_segments field from struct bio and struct request. Without virtual merge accounting they have no purpose. Signed-off-by: Mikulas Patocka <mpatocka@xxxxxxxxxx> --- block/blk-core.c | 1 - block/blk-merge.c | 31 ++++--------------------------- drivers/md/raid1.c | 3 --- drivers/md/raid10.c | 3 --- fs/bio.c | 12 +----------- include/linux/bio.h | 16 +--------------- include/linux/blkdev.h | 7 ------- 7 files changed, 6 insertions(+), 67 deletions(-) Index: linux-2.6.26-devel/block/blk-core.c =================================================================== --- linux-2.6.26-devel.orig/block/blk-core.c 2008-08-08 18:46:30.000000000 +0200 +++ linux-2.6.26-devel/block/blk-core.c 2008-08-08 18:47:59.000000000 +0200 @@ -2003,7 +2003,6 @@ void blk_rq_bio_prep(struct request_queu rq->cmd_flags |= (bio->bi_rw & 3); rq->nr_phys_segments = bio_phys_segments(q, bio); - rq->nr_hw_segments = bio_hw_segments(q, bio); rq->current_nr_sectors = bio_cur_sectors(bio); rq->hard_cur_sectors = rq->current_nr_sectors; rq->hard_nr_sectors = rq->nr_sectors = bio_sectors(bio); Index: linux-2.6.26-devel/block/blk-merge.c =================================================================== --- linux-2.6.26-devel.orig/block/blk-merge.c 2008-08-08 18:46:57.000000000 +0200 +++ linux-2.6.26-devel/block/blk-merge.c 2008-08-08 18:47:59.000000000 +0200 @@ -41,12 +41,9 @@ void blk_recalc_rq_sectors(struct reques void blk_recalc_rq_segments(struct request *rq) { int nr_phys_segs; - int nr_hw_segs; unsigned int phys_size; - unsigned int hw_size; struct bio_vec *bv, *bvprv = NULL; int seg_size; - int hw_seg_size; int cluster; struct req_iterator iter; int high, highprv = 1; @@ -56,8 +53,8 @@ void blk_recalc_rq_segments(struct reque return; cluster = test_bit(QUEUE_FLAG_CLUSTER, &q->queue_flags); - hw_seg_size = seg_size = 0; - phys_size = hw_size = nr_phys_segs = nr_hw_segs = 0; + seg_size = 0; + phys_size = nr_phys_segs = 0; rq_for_each_segment(bv, rq, iter) { /* * the trick here is making sure that a high page is never @@ -76,30 +73,17 @@ void blk_recalc_rq_segments(struct reque goto new_segment; seg_size += bv->bv_len; - hw_seg_size += bv->bv_len; bvprv = bv; continue; } new_segment: - if (nr_hw_segs == 1 && - hw_seg_size > rq->bio->bi_hw_front_size) - rq->bio->bi_hw_front_size = hw_seg_size; - hw_seg_size = bv->bv_len; - nr_hw_segs++; - nr_phys_segs++; bvprv = bv; seg_size = bv->bv_len; highprv = high; } - if (nr_hw_segs == 1 && - hw_seg_size > rq->bio->bi_hw_front_size) - rq->bio->bi_hw_front_size = hw_seg_size; - if (hw_seg_size > rq->biotail->bi_hw_back_size) - rq->biotail->bi_hw_back_size = hw_seg_size; rq->nr_phys_segments = nr_phys_segs; - rq->nr_hw_segments = nr_hw_segs; } void blk_recount_segments(struct request_queue *q, struct bio *bio) @@ -112,7 +96,6 @@ void blk_recount_segments(struct request blk_recalc_rq_segments(&rq); bio->bi_next = nxt; bio->bi_phys_segments = rq.nr_phys_segments; - bio->bi_hw_segments = rq.nr_hw_segments; bio->bi_flags |= (1 << BIO_SEG_VALID); } EXPORT_SYMBOL(blk_recount_segments); @@ -251,10 +234,9 @@ static inline int ll_new_hw_segment(stru struct request *req, struct bio *bio) { - int nr_hw_segs = bio_hw_segments(q, bio); int nr_phys_segs = bio_phys_segments(q, bio); - if (req->nr_hw_segments + nr_hw_segs > q->max_hw_segments + if (req->nr_phys_segments + nr_phys_segs > q->max_hw_segments || req->nr_phys_segments + nr_phys_segs > q->max_phys_segments) { req->cmd_flags |= REQ_NOMERGE; if (req == q->last_merge) @@ -266,7 +248,6 @@ static inline int ll_new_hw_segment(stru * This will form the start of a new hw segment. Bump both * counters. */ - req->nr_hw_segments += nr_hw_segs; req->nr_phys_segments += nr_phys_segs; return 1; } @@ -324,7 +305,6 @@ static int ll_merge_requests_fn(struct r struct request *next) { int total_phys_segments; - int total_hw_segments; /* * First check if the either of the requests are re-queued @@ -346,14 +326,11 @@ static int ll_merge_requests_fn(struct r if (total_phys_segments > q->max_phys_segments) return 0; - total_hw_segments = req->nr_hw_segments + next->nr_hw_segments; - - if (total_hw_segments > q->max_hw_segments) + if (total_phys_segments > q->max_hw_segments) return 0; /* Merge is OK... */ req->nr_phys_segments = total_phys_segments; - req->nr_hw_segments = total_hw_segments; return 1; } Index: linux-2.6.26-devel/include/linux/bio.h =================================================================== --- linux-2.6.26-devel.orig/include/linux/bio.h 2008-08-08 18:46:29.000000000 +0200 +++ linux-2.6.26-devel/include/linux/bio.h 2008-08-08 18:47:59.000000000 +0200 @@ -79,21 +79,8 @@ struct bio { */ unsigned short bi_phys_segments; - /* Number of segments after physical and DMA remapping - * hardware coalescing is performed. - */ - unsigned short bi_hw_segments; - unsigned int bi_size; /* residual I/O count */ - /* - * To keep track of the max hw size, we account for the - * sizes of the first and last virtually mergeable segments - * in this bio - */ - unsigned int bi_hw_front_size; - unsigned int bi_hw_back_size; - unsigned int bi_max_vecs; /* max bvl_vecs we can hold */ struct bio_vec *bi_io_vec; /* the actual vec list */ @@ -112,7 +99,7 @@ struct bio { #define BIO_UPTODATE 0 /* ok after I/O completion */ #define BIO_RW_BLOCK 1 /* RW_AHEAD set, and read/write would block */ #define BIO_EOF 2 /* out-out-bounds error */ -#define BIO_SEG_VALID 3 /* nr_hw_seg valid */ +#define BIO_SEG_VALID 3 /* bi_phys_segments valid */ #define BIO_CLONED 4 /* doesn't own data */ #define BIO_BOUNCED 5 /* bio is a bounce bio */ #define BIO_USER_MAPPED 6 /* contains user pages */ @@ -292,7 +279,6 @@ extern void bio_free(struct bio *, struc extern void bio_endio(struct bio *, int); struct request_queue; extern int bio_phys_segments(struct request_queue *, struct bio *); -extern int bio_hw_segments(struct request_queue *, struct bio *); extern void __bio_clone(struct bio *, struct bio *); extern struct bio *bio_clone(struct bio *, gfp_t); Index: linux-2.6.26-devel/include/linux/blkdev.h =================================================================== --- linux-2.6.26-devel.orig/include/linux/blkdev.h 2008-08-08 18:46:29.000000000 +0200 +++ linux-2.6.26-devel/include/linux/blkdev.h 2008-08-08 18:47:59.000000000 +0200 @@ -195,13 +195,6 @@ struct request { */ unsigned short nr_phys_segments; - /* Number of scatter-gather addr+len pairs after - * physical and DMA remapping hardware coalescing is performed. - * This is the number of scatter-gather entries the driver - * will actually have to deal with after DMA mapping is done. - */ - unsigned short nr_hw_segments; - unsigned short ioprio; void *special; Index: linux-2.6.26-devel/fs/bio.c =================================================================== --- linux-2.6.26-devel.orig/fs/bio.c 2008-08-08 18:46:30.000000000 +0200 +++ linux-2.6.26-devel/fs/bio.c 2008-08-08 18:48:00.000000000 +0200 @@ -229,14 +229,6 @@ inline int bio_phys_segments(struct requ return bio->bi_phys_segments; } -inline int bio_hw_segments(struct request_queue *q, struct bio *bio) -{ - if (unlikely(!bio_flagged(bio, BIO_SEG_VALID))) - blk_recount_segments(q, bio); - - return bio->bi_hw_segments; -} - /** * __bio_clone - clone a bio * @bio: destination bio @@ -352,7 +344,7 @@ static int __bio_add_page(struct request */ while (bio->bi_phys_segments >= q->max_phys_segments - || bio->bi_hw_segments >= q->max_hw_segments) { + || bio->bi_phys_segments >= q->max_hw_segments) { if (retried_segments) return 0; @@ -394,7 +386,6 @@ static int __bio_add_page(struct request bio->bi_vcnt++; bio->bi_phys_segments++; - bio->bi_hw_segments++; done: bio->bi_size += len; return len; @@ -1387,7 +1378,6 @@ EXPORT_SYMBOL(bio_init); EXPORT_SYMBOL(__bio_clone); EXPORT_SYMBOL(bio_clone); EXPORT_SYMBOL(bio_phys_segments); -EXPORT_SYMBOL(bio_hw_segments); EXPORT_SYMBOL(bio_add_page); EXPORT_SYMBOL(bio_add_pc_page); EXPORT_SYMBOL(bio_get_nr_vecs); Index: linux-2.6.26-devel/drivers/md/raid1.c =================================================================== --- linux-2.6.26-devel.orig/drivers/md/raid1.c 2008-08-08 19:01:55.000000000 +0200 +++ linux-2.6.26-devel/drivers/md/raid1.c 2008-08-08 19:04:10.000000000 +0200 @@ -1297,9 +1297,6 @@ static void sync_request_write(mddev_t * sbio->bi_size = r1_bio->sectors << 9; sbio->bi_idx = 0; sbio->bi_phys_segments = 0; - sbio->bi_hw_segments = 0; - sbio->bi_hw_front_size = 0; - sbio->bi_hw_back_size = 0; sbio->bi_flags &= ~(BIO_POOL_MASK - 1); sbio->bi_flags |= 1 << BIO_UPTODATE; sbio->bi_next = NULL; Index: linux-2.6.26-devel/drivers/md/raid10.c =================================================================== --- linux-2.6.26-devel.orig/drivers/md/raid10.c 2008-08-08 19:01:58.000000000 +0200 +++ linux-2.6.26-devel/drivers/md/raid10.c 2008-08-08 19:04:19.000000000 +0200 @@ -1334,9 +1334,6 @@ static void sync_request_write(mddev_t * tbio->bi_size = r10_bio->sectors << 9; tbio->bi_idx = 0; tbio->bi_phys_segments = 0; - tbio->bi_hw_segments = 0; - tbio->bi_hw_front_size = 0; - tbio->bi_hw_back_size = 0; tbio->bi_flags &= ~(BIO_POOL_MASK - 1); tbio->bi_flags |= 1 << BIO_UPTODATE; tbio->bi_next = NULL; -- To unsubscribe from this list: send the line "unsubscribe linux-scsi" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html
